Maximum depth of bedding layer? - Laying new patio

[decso]

I started a DIY job building a patio last weekend with the help of a mini digger to remove the topsoil 'clay - subsoil' from the area we plan to place the patio on. I've looked through the website for advice and it is fantastic but I'm unsure of one point: I've ordered 20 tons of grit sand for the bedding layer and don't plan to place a sub base down because: Its already there around the path edges and also once I removed the soil from the top 10-20 cm, all I was left with was compacted stone rubble. getting to my question: Is it OK to have a 20cm compacted bedding layer of grit sand or will this cause problems downstream?
Thanks for any advice offered.

[Tony McC]

200mm of bedding is way, WAY too much. It WILL move/settle over time. A bedding layer for flags or blocks should never be more than 50mm in depth.

[decso]

Thanks for the reply Tony,

In hindsight it seems like a pretty stupid sort of question, but when you're not sure its better to ask!
I read through the site in more detail and deceided in the end to use 10mm gravel for the subbase and 5cm of 1:10 cement & sand for the bedding layer. My back was broken from putting them down, but it does look great now the job is finished.
Thanks to all who helped put this site together, its by far the best patio site i've seen on the web.

regards,

Declan,
Ireland.

[Tony McC]

You're right, Declan, that it's better to ask than to guess, and I;m glad itl;s worked out for you. However, 10mm gravel is not the best thing to use as a sub-base. For future reference, in Ireland, we refer to the best sub-base material as "804" - this is exactly the same as the "Type 1" used in Britain, just a different name.

All who put the site together? There's only me! I wish I did have a team to help out, sometimes!